Process for making matrices.



E. R. RICHARDS.

PROCESS FOR MAKING MATRICES.

APPLICATION FILED NOV. 15. I916- .Patented Apr. 10, 1917.

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Add g5 I av na g PATENT OFFIQE.

ERNST R. RICHARDS, OF CHICAGO, ILLINOIS, ASSIGNOR TO SEARS, ROEIBUCK AND COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF NEW YORK.

rnoonss ron MAKING MATRICES.

Specification of Letters Patent, i lPat tsntugd Apr. it), 1191 31 Application filed November 15, 1916. Serial No. 131,362.

I To all whom it may concern:

Be it known that I, ERNST R. RIC ARDS, a citizen of the United States, residing at Chicago, in the county of Cook andState of Illinois, have invented certain new and useful Improvements in' Processes for Making Matrices, of which the following is a specification.

In printing with the ordinary electrotype plate, it is customary to place an overlay on the impression cylinder so as to get properly graduated pressure in the printing opera tion. taking a proof of the printing plate on hard paper, cutting out the high lights or lighter tones of the subject and retaining the darker portions of the proof, and pasting pieces of paper, upon the darker portions of the proof, the thickness of the overlay being graduated by adding several thicknesses of paper where needed. The overlay is hung on the impression cylinder opposite the place where the impression of the printing plate strikes, so as to register exactly with the impression.

In multi-color printing, the different colors of the same plate strike exactly the same place on the impression cylinder, and

therefore it is not possible to place overlays or do any make-ready on the impression cylinder. This difficulty is overcome by treating the plate in such a manner that, when the plate is put upon the press, the pressure upon the printing elements of lpge e includes the use of a matrix, which matrix is ordinarily produced as follows:

' A proof is taken while the plate is in the condition in which it comes from the electrotyper, for the purpose of ascertaining What defects, if any. there are in the plate and for determining the corrections that must be made therein and also for determining the particular portions of the plate which should be madeto printrespectively light and heavy. The workmanthen cuts out of the proof sheet thoseportionsof the impression which are to be printed heavier and pastes upon theproof sheet pieces of paper at those portions of the impression which are to be printed lighter, the strength of the impression being graduated by adding several thicknesses of paper where needed. The proof sheet thus cut out and built up is termed a matrix and is used for the pur- The overlay is commonly made by pose of producing in the face of the plate'a series of depressions and elevations the re verse ofthose produced in the matrix, so that when an impression is thereafter taken from the plate the elevated portions of the facewill yield the darkest impressions and the depressed portions of the plate the v lighter impressions. In producing, said elevations and depressions in the face of the plate, the matrix and the printing plate are placed face to face and subjected to sufficient pressure in any suitable manner and by any preferred apparatus so that those elements of the printing plate which should make light impressions shall be depressed more or less in accordance with the strength of impression desired.

It will be evident that the production of a matrix in the manner hereinbefore described requires a high degree of skill and many hours time. Owing to the method of production, it is scarcely possible for even a skilled operator to produce a matrix in which the different shades and tones are accurately represented. The object of this invention is to provide a method whereby a,

matrix may be made with a minimum of hand-work and in a minimum length of' time, and whereby the matrix shall accurately indicate the diflerent tones and shades of the subject.

In the accompanying drawings, Figure 1 is'a fragmental face view of a matrix produced in accordance with my invention. Fig. 2 is a sectional view on a greatly enlarged scale, taken in the plane of dotted line 22 of Fig. 1.

In practising my improved process, the following steps may be employed: Inasmuch as the plate is sometimes greasy when received from theelectrotype foundry, it should be Washed with alcohol, benzin, or

other suitable solvent, to remove any grease or oil that may be upon the surface of the plate. The plate is then carefully and thor- T oughly inked with an oil-insoluble or greaserepelling material. Water may be used with satisfactory results. Preferably a quantity of glucose, glycerin or soap is dissolved in the Water, and, if desired, a pigment may 3 be added so that the operator may readily see the impression made with said material.

After theplate has been inked with the grease-repellingmaterial, an impression of the plate is taken upon a sheet of suitable 7 character. 7 While a is possible that various kinds of sheet material may be used, the material at present preferred is a special kind of paper consisting of a strong linen bond paper 1 about three one-thousandths of an inch thick having a chalk coating 2 about four one-thousandths of an inch thick. Sheets of other thicknesses may, however, be

used.

' A few minutes after the impression of the plate 'had been taken upon the paper .with the grease-repelling material, an impression of a plain smooth plate is printed over the entire plate impression upon the sheet. The material used in taking this solid impression is preferably a heavy greasy compound. The ink known to the trade as chalk-overlay ink may be satisfac- After the solid impression has been taken upon the sheet, the sheet is placed in an etching solution. This solution may be of any suitable character adapted to attack the grease-repelling ink with which theimpression of the'printing plate was taken upon the sheet, and capable of attacking the binder usedin the chalk coating. While various etching solutions may be used, the one preferably employed is a weak solution of calcium chlorid. Wherever the greaserepelling ink prevented the greasy chalkoverlay ink or resist from penetratingand adhering to the surface of the chalk, the chalk is washed away to a depth inversely proportional to the concentration of p the resist.

Various parts of the matrix are indicated in the drawings by reference letters a, b, c,

d, e, f, g, h andi, each part being designated by the same letter in the different views.

' a a indicate portions of the chalk .coating which were completely covered by the resist and therefore were not attacked bythe etching solution. 6 denotes a border line which was not covered by the resist,the chalk coating having therefore been removed along said .line by the etching solution and the rinsing operation, as indicated in Fig. 2. The letters 0, d, f and 9 denote portions of the chalk coating, said portions being of various thicknesses, depending upon the extent to which they were attacked by the etching solution. The letters e and h indicate places where the chalk coating has been wholly removed. Y

- After etching, the sheet is carefully rinsed in clean water and dried between blotters.

' When dried, the sheet is, or may be mounted upon a'su1table backing, as, for example,

.such printing plate wit etched sheetsmay be produced in the manner hereinbefore described, one being mounted -on top of the other, these sheets in turn being mountedupon a suitable backing, as, for example, a thing metal sheet. A contrast in the relief of from six to eight one-thousandths of an inch may thereby be obtained. If preferred, the paper may be made with a chalk coating of suflicient thickness to afford any desired relief.

.After baking, the matrix is ready for use in treating the printing plate in the wellknown manner. Preferably a thin sheet of hard paper is placed between the printing plate and the matrix before treatment begins, in order to prevent the high-light dots of the printing plate from penetrating the chalk.

If necessary, a somewhat higher degree of heat may be provided in the treatment of the printing plate when my improved matrix is usedthan when a cut and pasted matrix is employed.

The process herein disclosed is adapted for producing matrices to be used in the treatment of printing 'plates of all kinds and for all purposes.

It will be apparent that, by means of the process herein disclosed, a matrix may be produced in a small fraction of the time required to make a cut matrix, that the process maybe performed by unskilled. labor,

and that my improved matrix is greatly superior in accuracy to a cut matrix, and possesses greater and finer detail.

While the description and the appended claims refer to the materials with which the two impressions are made as inks, it W111 be understood that the use of pigments in said materials is merely incidental and is I done simply to render the impressions more easlly visible to the operator.

I claim as my invention:

1. The process of making a matrix for use in the treatment of a printing plate, which comprises taking1 an impression of a resist-repelling liquid upon a chalk-coated sheet, taking an impression from a smooth surface over the entire plate impression-with a resist, subjectin the sheet to an etching agent capable 0 loosening the chalk coating underlying the first impression, and rinsing and p drying the sheet. I

e process of making a matrix for use in the treatment-of a printing plate,

which comprises taking an ink impression of such printing plate upon a chalk-coated sheet, taking an impression from a smooth surfaceover the entire plate impression with an ink which is repelled by the first mentioned ink, subjecting the sheet to an etching agent capable of acting upon the chalk coating underlying the first impression, and rinsing and drying the sheet.

3. The process of making a matrix for use in the treatment of a printing plate, which comprises taking an impression of such printing plate with resist-repelling "material upon 'a chalk-coated sheet, taking an impression from a smooth surface over the entire plate impression with a resist, subjecting the sheet to an etching agent capable of attacking the resist-repelling material and the underlying chalk-coating, and rinsing and drying the sheet,

4. The process of making a matrix for use in the treatment of a printing plate, which comprises taking an impression of such printing plate with grease-repelling ink upon a chalk-coated sheet, taking an impression from a smooth surface over the 'entire plate impression with a grease ink,

subjecting the sheet to an etching agent capable of attacking the grease-repelling ink and the underlying chalk-coating, rinsing and drying the sheet, mounting the sheet upon a suitable backing and baking the sheet.

In testimony whereof, I have hereunto set 

